I'm a little shocked that you think warfare has two sides that are complicit when in reality it's full of young clueless kids who don't know what they're doing. Are you implying that soldiers are like UFC fighters on a ring? That there's some competitive element to killing in war and that makes rape worse than murder? I'm going to argue again that your argument is self-deprecating.
Rape happens a lot in war too, for strategic reasons. Are you going to argue that rape in war is also competitive?